... YMCA is the lone holdout (please tell me there are others with integrity on this issue) who has not lowered their minimum age to 10...
IANTD is still 12 for Jr. OW and 15 for OW.
I have no doubt that some 10 year olds, and even some much younger have the physical abilities needed to dive. I just finished certifying a teen (13 1/2) who could have passed all the physical skills at 6 or 7 years of age, but would have had very little understanding of the concepts behind why certain things were important.
I have 3 standards for when I will teach a child (these are my personal criteria)
1) Mental maturity: Student must be able to learn the concepts required. As part of my curriculum we cover formulas for calculating Rock Bottom, MOD, Best Mix, EAD and more. Until I am able to teach a student these concepts they are too young IMO. Most of this is basic algebra, and while I do not mind teaching someone how to do math, young children are only getting introduced to multiplication and division in 3rd-5th grades (8-10 yrs old) - makes learning how to calculate SAC and gas consumption difficult (Which is on the OW exam)
2) Physical Maturity: Do they have the stamina to carry their gear, perform the skills and complete a surface swim afterwards while towing another diver?
3) Emotional Maturity: Are they able to focus on more than just breathing. Do they have the situational awareness to safely be in the water.
Obviously some adults do not meet these requirements, but I'm a little more stringent with children because Adults have one thing children do not ... Experience.
btw - I normally like students to be 14 (the above case was an exception based upon LOTS of experience with the individual in question)
Just my .02 cents worth
Aloha, Tim
P.S. If a parent wishes to teach their own child ... now that's a whole other issue, but I'm not a parent, as a teacher I have limited time to work with and become familiar with the abilities of my students. A parent has years to develop and work with their own child.